Yeah HiDPI is a mess in wx applications currently.
The OS's have handled this differently, with GTK being behind of course.
wxWidgets have some support in 3.0.x release and more coming in 3.2.
wxWidgets sees 3.1 as a developer release so linux distributions don't distribute that,
the wxWidgets team never seems to finish 3.2, and patches 3.0 very little since all development is
on 3.1, sigh.
I have not owned a HiDIP screen so I have not had any problems with this, nor been able to test it,
thus basically ignoring the problem altogether until the world came up with a solution of how to handle it.
OBSERVER_SCALE was a temporary hack to make it work a couple of years ago, I don't remember the
discussion but it might have been a PR or something I did for Loic after a discussion on this mailing list.
So this is a mess, and I could really need some help from someone jumping into the rabbit hole.
There are probably some functions in wx-api that are missing, and we need to scale the fonts and drawing done
in the observer tabs.
/Dan